Binary phase shifter based on liquid crystal

Abstract

Proposed is a liquid-crystal-based binary phase shifter using a liquid crystal, a material in the spotlight in the super-high-frequency field. The liquid-crystal-based binary phase shifter includes a phase shift circuit board having an upper substrate and a lower substrate combined each other with a spacer having a liquid crystal cell gap therebetween, a liquid crystal being inserted into the spacer; metal vias provided at opposite ends of the upper substrate with transmission lines between the metal vias; and a phase shift meander line provided on a lower metal ground plane placed between the metal vias positioned at the opposite ends, wherein phase shift regions of the lower metal ground plane are selectively divided and bias is discretely applied by region. Beyond the use of a liquid crystal in an RF circuit, a unique method of applying a bias voltage is proposed for a variable speed of the liquid crystal, thereby obtaining the maximum phase shift amount and the highest response speed.

What is claimed is: 
     
         1 . A liquid-crystal-based binary phase shifter, comprising:
 a phase shift circuit board having an upper substrate and a lower substrate combined each other with a spacer having a liquid crystal cell gap therebetween, a liquid crystal being inserted into the spacer;   metal vias provided at opposite ends of the upper substrate with transmission lines between the metal vias; and   a phase shift meander line provided on a lower metal ground plane placed between the metal vias positioned at the opposite ends,   wherein phase shift regions of the lower metal ground plane are selectively divided and bias is discretely applied by region.   
     
     
         2 . The liquid-crystal-based binary phase shifter of  claim 1 , wherein the phase shift circuit board is configured to obtain a plurality of phase differences depending on whether a maximum voltage is applied to the phase shift regions, and obtain all phase shift values from 0 degrees to 330 degrees at regular intervals. 
     
     
         3 . The liquid-crystal-based binary phase shifter of  claim 1 , wherein the phase shift circuit board is configured to realize phase shifts from 0 degrees to 330 degrees by turning on and off a bias voltage for each of the phase shift regions, the bias voltage being indicated by a number 1 or 0. 
     
     
         4 . The liquid-crystal-based binary phase shifter of  claim 1 , wherein bias electrodes are separated by region to apply different bias voltages to the respective regions of the phase shift circuit board, and
 the metal ground plane is separated while the meander line is left intact.   
     
     
         5 . The liquid-crystal-based binary phase shifter of  claim 1 , wherein the phase shift circuit board has the metal ground plane located at the upper substrate, and bias electrodes for the respective regions are located at a layer immediately on the metal ground plane, thereby achieving bias separation and allowing RF to pass through.